Tractor



FIG. 1 is a front perspective view of a tractor showing our new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a front view thereof; and,

FIG. 7 is a rear view thereof.

The bottom view forms no part of the claimed design.

The dashed broken lines and the dotted lines in the Figures are included for the purpose of illustrating portions of the tractor that form no part of the claimed design. 

The ornamental design for a tractor, as shown and described. 